Process for preparing aryl halosilanes



Patented June 27, 1950 rRooEss For: PREP RING ARYL HALOSILANES George H.Wagner, Kenmore, -Y., assignor to The Linde Air Products Company, acorporation of Ohio No Drawing. Application October 10,1947,,SerialNo.779,202 I I The invention is a process for the manufacture ofaryl halosilanes, in which process an aromatic hydrocarbon is caused toreact with a silicon compound containing at least one Si-Sibond in themolecule.

Aryl halosilanes have been prepared in various Ways, for example by theGrignard reaction as modified by F. S. Kipping and others; and byvarious adaptations of the Wiirtz synthesis. These methods requireexpensive reagents. The aryl halosilanes have also been prepared by thedirect action of aryl halides on silicon, but the yields obtainable inthis way are believed to be relatively poor. It has also been statedthat hydrocarbons, apparently of all known classes, can be reacted invapor phase with compounds which contain silicon and halogen to form,among other things, aryl halosilanes. In this latter process a stream ofthe mixed vapors is heated to at least 450 0., and preferably above 600C., and no catalyst is used. Compounds containing a plurality of siliconatoms in the molecule are represented to be suitable starting materials,but the products obtained from them are not identified. I have beenunable to obtain satisfactory results with the process last referred to.

The process forming the subject matter of the present applicationrequires a, silicon compound containing the Si-Si bond, and alsorequires a sulphur-containing catalyst. The temperatures used are below600 (3., and usually below 450 C., with the reagents preferably at apressure not less than that generated by the confined vapors at 200 C.

The reaction is effectively catalyzed by a wide variety ofsulphur-containing materials. I have used, for example, elementalsulphur, sulphur monochloride, diethyl sulphide, butyl mercaptan, andcarbon disulphide. Sulphur monochloride is convenient and quite active.Fairly high catalyst concentrations are desirable. Thus, when 66 gramsof benzene was heated with 113 grams of SizCls at 350 C. for 14.5 hoursin the presence of a quantity of SzClz equal to 0.05% of the wholecharge, the yield of CsHsSiCls was only 2.7%, and the efficiency (basedon the silicon content) 2.8%: when the concentration of S2012 wasincreased to 0.50%, other conditions remaining the same, the yield roseto 14.7%, and the efiiciency to 15.5%: while with 4.0% of the catalyst,yield and efiiciency were both 25.4%. In the above tests, a bomb linedwith the alloy known as Monel K was used. This metal seems to beespecially favorable to the reaction, but other 6 Claims. (01. 260-4462,)

materials, for example stainless steel, can

The reaction is expedited by raising the tembe used.

' hours may be required, but this is usually unobjectionable in acommercial operation.

The chief utility Of the invention seems to be in the treatment ofhalogenated derivatives of the disilanes, such as SizCls or SizHCls, tomake such relatively simple products as Cal-158K313, but derivatives oftrisilanes and their higher homologues can also be used, withcorresponding diversity in the products. Derivatives of diandpolysilanes containing other substituent groups, such as alkoxyradicals, with or instead of halogen, are also available. Thehydrocarbon may be as simple as benzene, toluene, or Xylene, but theprocess is applicable to aromatic hydrocarbons in general.

The following specific examples will serve further to illustrate theinvention:

Example I A mixture consisting of 66 grams of benzene, 113 grams ofhexachlorodisilane, and 8 grams of sulphur monochloride was heated at350 C. for

'16 hours in a 300 cc. autoclave. From the products there were recovered42 grams of phenyltrichlorosilane, 43 grams of benzene, 6 grams ofhexachlorodisilane, and 56 grams of silicon tetrachloride.

Under the same conditions, but with a catalyst consisting of 3 grams ofelemental sulphur, the quantity of phenyltrichlorosilane recovered was39 grams, with 42 grams of benzene, 15 grams of trichlorosilane, and 46grams of silicon tetrachloride.

Ezcample II A mixture of grams of toluene, 113 grams ofhexachlorodisilane, and. 8 grams of sulphur monochloride was heated at290 C.-350 C. for 24.5 hours in a 300 cc. autoclave. The quantity oftolyltrichlorosilane recovered was 20 grams.

Example III A mixture of 66 grams of benzene, cc. ofpentachlorodisilane, and 8 grams of sulphur monochloride was heated at350 C. for 16 hours in a 300 cc. autoclave. Phenyltrichlorosilane in theamount of 49 grams was isolated from the products.

What is claimed is:

1. Process of preparing aryl silicon compounds which comprises heating amonocyclic aromatic hydrocarbon with a fully chlorinated disilane, inthe presence of sulphur monochloride, and at a pressure not less thantheir combined vapor pressure at 200 C.

2. Process of preparing phenyltrichlorosilane 5 which comprises heatingtogether benzene, 'hexa chlorodisilane, and sulphur monochlorideinr'an"autoclave to a temperature between 200 C. and 450 C. 1

3. Process of preparing phenyltrichlorosilane.

which comprises heating together benzene} pentachlorodisilane, andsulphur monochloride in an' autoclave to a temperature between 200.C.and

4. Process of preparing aryl silicon compounds 15 which comprisesheating a. monocyclic aromatic hydrocarbon with a member of the groupcon;

sisting of pentachlorodisilane and hexachlorodisilane, in the presenceof a catalyst ofthe group consisting of elemental sulphur, sulphur 20monochloride and carbon disulphide, and rat a pressure not less than thecombined vapor pressure ofthe reactantstat 200. C. w. h

5. Process of preparing aryl silicon compounds whichcomprises heating a,monocyclic' aromatic 254 sisting of pentachlorodisilane andhexachlorodisilane, in the presence of carbon disulphide, and

' at 'a' pressure" not less than the combined vapor pressure of thereactants at 200 C.

7 GEORGE H. WAGNER.

2 REFERENCES CITED .TIThe following ;references are of record in th fileof this patent:

, UNITED STATES PATENTS Number Name Date 2,379,821. Miller July 3,19452,405,019 Dalin July 30, 1946 2,407,181 Scott Sept. 3, 1946 2,474,087 1Barry June 21, 1949

1. PROCESS OF PREPARING ARYL SILICON COMPOUNDS WHICH COMPRISES HEATING AMONOCYCLIC AROMATIC HYDROCARBON WITH A FULLY CHLORINATED DISILANE, INTHE PRESENCE OF SULPHUR MONOCHLORIDE, AND AT A PRESSURE NOT LESS THANTHEIR COMBINED VAPOR PRESSURE AT 200*C.